October 2022: Restoration and Rewilding at INTECOL 2022
By Dr Emily Waddell, Woodland postdoctoral researcher
INTECOL 2022 was my first time presenting at an international conference as COVID-19 hit in my final year of my PhD and scuppered my plans to attend the Association for Tropical Biology and Conservation conference in Colombia. I was excited to have my talk accepted under the session ‘Restoration and Rewilding: upscaling activities to reverse global terrestrial ecosystem degradation’, moderated by RestREco’s Prof James Bullock (UKCEH) and Dr Nathalie Pettorelli from ZSL’s Institute of Zoology. As we were still in the middle of our field season, attending in person was going to be tricky, but luckily the conference was hybrid, allowing myself and others to participate online from home.
There were an interesting mix of talks and topics across the week, from the usual ‘impacts of climate change’, ‘land-use and biodiversity’, and ‘utilising remote sensing tools’ to more unusual but thought-provoking topics such as ‘Decolonizing science and fieldwork’. I enjoyed watching excellent plenaries each day, including ‘The ecological and social shaping of functional diversity’ and ‘Sensory pollution in urban environments’, which featured some great audio and animations! There were always several sessions running in parallel, which meant it was difficult to choose which to watch live, but the perk of hybrid conferences is the ability to access recordings afterwards (see below for mine!).
The ‘Restoration and Rewilding’ session had a wide range of speakers from restoration projects across the globe, including ‘Active vs. Passive restoration in tropical South America’, ‘Restoring wildlife corridors in East Africa’ and the ‘Rewilding of the Chernobyl Exclusion Zone’. I particularly liked the discussions around defining ‘rewilding’ and ‘restoration’ (as these terms are often used interchangeably), and how these two potentially complementary approaches may be used together to meet common goals (including a talk by moderator Nathalie Pettorelli). Also, the importance of ‘not just having the parts present, but that the parts need to work together’. For example, you can’t plant tree seedlings and expect that a fully functioning forest with all the ecological processes and functions will develop! This is something which is at the heart of the rationale behind the RestREco project, that restoration projects should aim to restore complex, high functioning ecosystems, which are resilient to future environmental change.
At the end of the session there was time allocated to a wider discussion between moderators, speakers, and the audience. One of the topics discussed was if disturbed areas are left with no active interventions by humans, will non-native (and potentially invasive) species just take over, and if so, is this a problem that needs to be actively managed, or is this just part of ‘rewilding’ that we need to accept. As someone who did their PhD on invasive species (see here if you are interested!), it is a topic I found particularly interesting and in my opinion the answer is both….As the planet becomes more and more connected, and the environment is changing, it is inevitable that non-native species will spread faster than we can control. Also, if some of these non-natives are able to adapt to the changing climate better than similar native species, then they may become an important part of future restored species communities, especially if they can restore functions or processes that have been lost from the ecosystem. In addition, most non-native species pose little harm to the native community with only 10-15% considered ‘invasive’, meaning they cause ecological and/or economic harm. Thus, when restoring ecosystems, I think we should strive to control highly invasive non-native species that could dominate the recovering species community, both known invasives and any newly introduced species that have the potential to become invasive (identified through risk assessments based on species’ biology, geographic origin, and pest status elsewhere).
This conference and session gave me lots of food for thought as I begin to think about analyses and write up of the RestREco data we’ve collected so far, and the plans for our management intervention experiment.
Click on the video below to hear a recording of my talk!
September 2022: Crispy chalk grasslands and withered woodlands – the impact of summer’s drought
By Dr Ben Woodcock, Ecological Entomologist at UK Centre for Ecology & Hydrology
Fieldwork is in full swing across the chalk grasslands in southern England. As stunning as this area can be under normal conditions, the recent drought has had a profound impact. July 2022 saw record temperatures and with much of southern England receiving only around 20% of the rain of an average July. Some areas in southern England received even less than 10% of the average rainfall. This has wreaked havoc on these grasslands, leaving them arid and brown with much of the normally all too evident insect life absent. The browning of the grasslands has been so widespread that it can easily be seen on satellite imagery.
SENTINEL-3 satellite image from August of Great Britain showing the intensity of the summer drought (Photo credit: @spatialanalysis/Twitter)
This has caused some issues for our surveys and we have had to postpone some elements of the fieldwork for now. It is a struggle to do pollinator surveys if there are no plants in flower and measuring water infiltration rates on bone dry soil is also far from ideal. Moreover the dry weather has caused issues for farmers. Grasslands that were not originally going to be grazed had sheep moved into them as the other fields did not have much to offer the sheep anymore!
A grassland field site in Oxfordshire turned brown with barely any green left and sheep grazing in distance (left); one of our Wiltshire grassland sites on 16th June 2022 (top right) and the same field on 11th August 2022 (bottom right)
While it would be nice to say these temperatures are unprecedented, this is another in a string of years where what may have once been considered unheard of temperatures are reached on a regular basis. What will be the long term impact for the communities of plants, insects, birds, mammals and microbes that inhabit these grasslands? This is true not just for these areas where restoration is being attempted, but also for the historic species-rich chalk grasslands (e.g. Salisbury Plain) which have typically formed the target communities for such restoration projects. It is highly likely that what we currently perceive as ‘species-rich chalk grassland’ represents a transient community that is the product of relatively recent climatic and management conditions, and one that may have been compositionally quite different in even the recent past. For example, during the Medieval Warm Period (somewhere between 1000-1200) or the Little Ice Age (1400-1800). While this is undeniably a beautiful and diverse community, both its long term persistence under climate change and its historical basis for use as a reference community to which restoration should aspire needs to be questioned. Indeed, this is one of the core aspirations of the RestREco project. To try and understand how restoration (both for grasslands and woodlands) can be developed in the future in a way that moves beyond this paradigm of simply trying to replicate idealised historic communities, and by doing this addressing the need to ensure that these restored habitats are robust to the ongoing perturbations that will threaten them in the coming years and decades. While this does not necessarily mean that many of the species we consider typical of calcareous grasslands may not continue to be a mainstead of restored grasslands in the future, it does introduce flexibility so that the focus may move away from simply species composition, to the capacity of these systems to remain resilient in the ecosystem processes that they underpin.
Walk into woodland site near Market Bosworth showing dried out grassland (left); Sycamore tree with leaves turning brown in August (middle) and ‘false Autumn’ at a woodland site near Northampton on 15th August 2022 (right)
In particular, it is the underlying complexity of the trophic interactions, across a range of taxonomic, spatial and temporal scales that may be the key to delivering restored grasslands robust to environmental change. This focus away from traditional endpoints for grasslands restoration (e.g. species-rich chalk grasslands) gives a new flexibility that provides avenues of opportunity to future-proof our world to change. The ever more obvious impacts of climate change make this new focus vital for the future stability of the environment.
Photo credits: Maico Geert Weites and Ross Barnett
August 2022: Analysing soil microbial complexity
By Dr Oscar Aguinaga Vargas, Soil postdoctoral researcher
One of the components of RestREco is the analysis of the soil microbiology of different restoration sites to determine soils complexity and to incorporate this new knowledge into ecosystem restoration. Soils are full of life, they contain an enormous diversity of living beings, including microorganisms (e.g., bacteria, archaea, fungi, protozoa), nematodes, collembola, mites, earthworms, termites, ants, among other forms of life. This vast biodiversity is mainly due to the heterogeneity of soils. In one landscape, we can find soils with different physical (e.g., texture, structure, porosity, permeability) and chemical (e.g., pH, salinity, nutrient content, organic matter) characteristics. Therefore, these different soil environments will create diverse habitats that can hold distinct forms of life. These variations also occur at the microscopic level (soil microhabitats). For example, oxygen availability in soils will determine the formation of microhabitats for aerobic, facultative, and anaerobic bacteria, all of them with different survival strategies (depending on whether they can use oxygen or other chemical compounds for energy production). These changes can be observed within a tiny scale of soil depth as oxygen concentrations can drastically change withing a few millimetres. Soil microorganisms are also connected to each other through different interactions. For example, microbes with a vast inventory of enzymes will breakdown complex food sources into more simple nutrients that allow specialized bugs to thrive. Following the oxygen example, those bacteria capable of using oxygen for energy production will modifying the chemistry of other compounds, making them suitable nutrients for other species with key roles such as sulphur and nitrogen cycling. In RestREco, we understand microbial soil complexity as the number of different microorganisms living in it, and the connections between them that are occurring in the different soil microhabitats.
Soil degradation is the decrease of soil chemical, physical and biological quality. This can lead to the loss of ecosystem services such as food production, water purification, carbon storage and climate regulation. Efforts to recover soil quality are focused on aboveground restoration, mainly revegetation and reforestation, with the aim to stabilize soil and provide organic matter. However, a key factor for successful soil restoration is located underground. The recovery of soil microbial communities, their diversity, and interactions are also necessary.
Thanks to our colleagues in the field, we have received several soil samples from grasslands and woodlands over the past months. The samples come from sites with distinct states (e.g. post-agricultural and post-industrial lands) and characteristics of restoration. We have designed and optimized a method for extracting DNA from all these samples. Over the past weeks, we have extracted DNA from all the organisms that inhabit or somehow left this molecular fingerprint on the soils; but for now, we will only focus on the microbial DNA (archaea, bacteria and fungi).
Clockwise from top left: Undergraduate students Georgia and Will collecting soil samples; Sam, Ross and Emily sampling soil (‘mud’) in the rain; Measuring out the top 10cm from a soil sample in a Scottish post-agricultural woodland; Clay soil in a post-agricultural site; Two soil samples from post-industrial woodland sites, showing pieces of brick and coal.
We are expecting between 1 – 3 million microbial DNA sequences per samples that we will analyse through DNA metabarcoding. This approach will help us determine the taxonomy and abundance of the microbiome of each sample. The results obtained will allow us to elucidate the taxonomic structure of the soil microbiomes (necessary to understand its complexity). Moreover, we will be able to correlate the taxonomy with environmental factors (chemical and physical soil properties) and with soil functions (litter degradation, nitrogen fixation) to determine whether these variables influence taxonomic assemblages.
Oscar in the lab carrying out DNA extractions (left) and sieved, grounded and dried soil samples ready for nutrient analysis (right)
The next information we need to measure complexity is the connection between the taxonomic groups. This is where things get more complicated as we are reaching the boundaries of DNA technology and data analysis. Evaluation of microbial association networks is a topic still under development and no validated experiment for assessing microbial ecological network exists.
Because we will be able to know which taxonomic groups are present or absent in all our samples, one approach we intend to use is the analysis of co-occurrence, which is a long-term method to infer different types of interactions in ecological systems. Even though this method may not detect real biotic associations, it has proven to be suitable for getting an idea of microbiome complexity, which is a good start. We are still brainstorming other suitable approaches which may involve more intricated statistical methods of inference. More to come!
Photo credits: Oscar Aguinaga Vargas, Emily Waddell, Ross Barnett, Sam Rogerson
July 2022: Multi-functionality in ecological restoration
By Dr Emily Waddell, Woodland postdoctoral researcher
The aim of RestREco is to consider complexity, multi-functionality, and resilience as fundamental aims for restoration projects, rather than attempting to re-create specific reference ecosystems. The rationale for this is two-fold: (1) “pristine” reference ecosystems are hard to define, and (2) climate change is leading to a shifting baseline, and there is a need to restore ecosystems that are resilient to future pressures (i.e. environmental change). There is a large theoretical and conceptual literature that links ecosystem complexity to resilience and stability, to the supply of multiple functions and services, and to the conservation of biodiversity. But what a “complex ecosystem” looks like, and how complexity influences functions and resilience, remains largely unstudied in real-world landscapes.
Last year, we collected a whole suite of ecological data within each of our 132 grassland and woodland sites which will allow us to calculate different measures of ecological complexity (e.g. species richness, structural complexity, acoustic complexity, food web complexity). Ultimately, determining how ‘complex’ each individual grassland or woodland is. Now, in a subset of sites, we are collecting data on the next aim, ‘multi-functionality’, which requires more detailed work on a range of ecosystem functions (e.g. litter decomposition rates, pollination services, and herbivory and predation rates). These sites were selected to represent a gradient in complexity, to quantify if and how complexity supports net gains in the emergent functionality of ecosystems.
We are expecting complexity to enhance multiple ecosystem functions, such as decomposition, carbon capture and pollination, through more efficient resource capture and transfer, greater standing stocks and richness of producers and prey, and a diversity of interactions and niches. For example, the more species there are in an ecosystem, the higher the likelihood that multiple species perform similar functions, and so essential functions are maintained even if one species is lost from the ecosystem. This is known as functional redundancy and is a key mechanism linking complexity and resilience.
A conceptual diagram depicting increasing degrees of ecological complexity within a system (Figure 1 in Bullock et al. (2021) Ecography)
For more information on this topic, please see our recent peer-reviewed publication in Ecography, entitled “Future restoration should enhance ecological complexity and emergent properties at multiple scales”, and the references within.
From the field:
Starting ecosystem function measurements in Scottish Woodlands
By Ross Barnett, Woodland research technician
Our fieldwork this month has focused on quantifying four key ecosystem functions in our 18 woodlands: pollination, predation, herbivory and parasitism. Each has been investigated using a different set of observations and field experiments.
First up, is our pollination experiment. We chose the widespread creeping buttercup (Ranunculus repens) as the model species for this. The experiment simply involves finding a buttercup plant with two unopened flower buds. We cover one bud with a small organza bag, to stop pollinating insects accessing it, and the other bud is marked with red string, serving as a control. Over the following weeks, we returned to harvest the seed heads from all bagged and unbagged flowers, which will be dried in the lab before counting the number of seeds produced by each flower.
Next is our predation experiment using artificial caterpillars. Our field team of undergraduate students painstakingly crafted 1440 caterpillars using non-toxic green plasticine (yes, really!), which have been deployed in our woodlands, on tree branches and on the ground. Plasticine is an ideal material for this experiment because it is strong enough to hold the caterpillar shape, but soft enough that any bite marks from foraging insects, birds and rodents are easily identifiable. This is a fairly commonly used method to quantify relative levels of predation within habitats. After several days in the field, the caterpillars are collected, and the bite marks counted and identified to predator.
Clockwise from top left: Pollination exclusion experiment on creeping buttercup; pollinator of buttercup, Oedemera nobilis; predation of artificial caterpillar on branch by birds; predation of artificial caterpillar by slugs or snails; predation on ground by birds; predation by rodents.
To quantify insect herbivory on trees, we focused on our two most common groups of trees: oak and birch. At each site, we gathered branches from each species using telescopic pruning shears to make sure the leaves were out of reach from grazing deer or livestock. On each branch, the first ten fully developed leaves were chosen, and the percentage leaf area grazed was estimated by eye into categories of herbivory. The same observer estimated these measurements to keep it consistent across sites.
Finally, we have been gathering leaves with evidence of leaf-mining activity by insect larvae. The larvae of several beetles, flies, butterflies, and moths use leaf mines as a means of feeding and pupating with additional protection from predators. Many parasitic wasps, however, will lay an egg inside the leaf-mining larva, benefiting also from the protection of the mine, whilst the wasp larva feeds on the leaf-miner from the inside out (yikes!). Our collection of mined leaves is being kept in an insectary whilst we wait for either the emergence of an adult leaf miner or a parasitic wasp!
Clockwise from top left: Birch branch; Two leaf miners on a hawthorn leaf; Leaf miner on an oak leaf; Insect larvae eating an oak leaf; Two tiny larvae eating a birch leaf; Emily looking for leaf miners in a nettle leaf; Ross using telescopic pruning shears to cut down branches.
Ultimately, we will use these data to compare pollination rates, predation, herbivory, and parasitism within each woodland along our complexity gradient.
Doing your undergraduate project with RestREco!
By Will Crook, final year Ecology student at University of Stirling
I’m currently working on my dissertation investigating how biodiversity influences ecosystem function in Scottish woodlands. I was drawn to this topic as I feel there is a dire need to help mitigate the global biodiversity crisis and joining the RestREco project seemed a way I could be well applied, restoring ecosystems close to home.
When I started summer fieldwork in June, I was surprised as to how much there was in the woods that I hadn’t noticed before! Once time is spent looking for leaf miners or buttercups, everything else is revealed including cyan mushrooms, iridescent beetles, napping bumblebees, and cute sawfly caterpillars. Collecting data as part of a team is a feeling that you’d struggle to beat; working hard and getting things done, while still finding time to crack jokes and have a laugh. The jokes become necessary once it starts to rain, although oftentimes those are the most fun days. I’m excited to continue researching over the summer, my knowledge of the natural world is expanding, my efficiency with fieldwork is improving, and I am gaining an immunity to nettle stings.
Top to bottom and left to right: Ross looking at sawfly larvae on birch; Will, Emily, Ross and Dominic in a sycamore tree; Georgia with Teddy (the fieldwork dog); Forget-me-not flowers; Leaf beetle on willow; Two weevils on birch; Moth on a nettle; Emily, Georgia and Will ‘enjoying’ the Scottish summer weather.
All photos taken within our 18 subset woodland sites.
Photo credits: Emily Waddell, Ross Barnett, Will Crook
June 2022: National Trust and the RestREco project
By Ben McCarthy, Head of Nature Conservation & Restoration Ecology at National Trust
With the UN’s Decade of Ecosystem Restoration well underway and increasing recognition that Nature Based Solutions are crucial in meeting the twin climate and biodiversity crises just how should we achieve our international targets and start bending the curve to achieve environmental net gain?
The UK’s recent political path has thrown wide open how best to reconfigure a national approach to meeting obligations emerging from the post-2020 UN Biodiversity Framework such as 30×30. The UK’s departure from the EU and it’s powerful nature directives mean that how the UK and devolved nations deliver against international commitments is up for debate. Alongside this, emerging plans to deliver the UK Government’s ambitious 25 Year Plan for the Environment means this is an important moment in time to ensure a Green Brexit and, as the current incumbent at No 10 might say, ‘build back better’.
The Westminster Government’s response was set out in their Nature Green Paper and recent consultation on associated targets. Whilst in many ways these adopt a traditional approach to meeting our international biodiversity commitments with various targets for species, habitat and nature recovery networks it also throws wide open how best to recover nature and measure this success.
Whilst many commentators may assess the government’s plans as ‘work in progress’ there remains a more fundamental challenge for researchers, policy makers and practitioners of how to rebuild nature for a changing future. A challenge that should not be shied away from. This issue comes into sharp focus for the National Trust as we fully recognise, as a major landowner, the critical role land use and management will play in achieving our strategic priorities for Net Zero and Nature’s Recovery.
Ensuring our delivery realises our ambition and secures more resilient ecosystems will clearly be key to delivering our twin priorities. Yet blindly chasing indigenous reference states or pristine plant communities may not be the most appropriate approach to tackling the challenges of the Anthropocene. And so our collaboration with the RestREco team to investigate how to create the architecture and functionality from our degraded land. The real-life significance of such endeavours should not be underestimated – and not only to justify the £300M/yr agri-environment budget being asked of HM Treasury. Nature’s recovery is fundamental to society’s ability to meet the climate challenge and core to our charitable purposes.
So I remain open and excited about shining light on a new paradigm for target setting for nature’s recovery that is based on a greater understanding of characteristics of functionally intact systems for all our benefits.
Visit the National Trust’s website to find out more about their many restoration projects http://www.nationaltrust.org.uk
From the field:
Measuring complexity at National Trust’s Slindon Estate
By Ross Barnett, Woodland research technician
We recently visited National Trust’s Slindon Estate, in West Sussex, to conduct surveys of flora and fauna that will provide us with data to characterise the ecological complexity of the newly wooded areas within the estate. Slindon is one of two ‘rewilding wildcard’ sites for the RestREco project that have taken unique approaches towards woodland regeneration – in this case, excluding herbivores with a deer fence, and allowing seed dispersal and natural colonisation from the surrounding woodland. Our complexity measures will combine data from tree surveys, understorey plant communities and insect abundances, along with soundscape recordings from earlier in the spring, to see how this ‘wildcard’ compares to our more traditional woodland creation sites. Whilst sampling the lower branches of trees at Slindon, we noticed high numbers of the metallic green Phyllobius weevils (species TBC!), which often feed on the buds and leaves of willow trees (Salix spp.), which dominate the tree community at this site.
Clockwise from top: Young trees within deer fenced ‘wildcard’ woodland at Slindon Estate; farmland matrix surrounding woodland within Slindon Estate; Phyllobius weevil; Dr Matt Guy and Prof. Kevin Watts identifying ground flora in the field. Photo credits: Ross Barnett and Sam Rogerson (weevil).
April 2022: Exploring the complexity of grasslands
By Maico Geert Weites, Grassland research technician
Grasslands come in many shapes and sizes and the Southern English grasslands we study overwhelmingly comprise chalk grassland. Chalk grassland is a man-made habitat that was created by the logging of woodland by neolithic farmers in the chalk districts of England. This created an open steppe-like landscape. The shallow soils were often poorly suited for crop cultivation and were used as grazing grounds for cattle and sheep.
One may be under the impression that such infertile man-made landscapes are perhaps not that species-rich, however they are amongst the most biodiverse habitats in the UK and are essential for the survival of everything from Chalkhill Blue and Sainfoin Blunthorn Bee to Burnt-tip Orchid and Great Bustard.
The open plains gradually came under pressure from enclosure and agricultural intensification throughout the 19th and 20th centuries and many were either converted into arable land or were otherwise agriculturally improved to be more productive. Species-rich chalk grasslands made way for wheat and grazing grounds dominated by Perennial Ryegrass. The period between 1940 and 1984 saw a reduction of the British chalk grassland area by 80%. Looking at unimproved grasslands more broadly a decrease of 93% was observed between 1932 and 1984 in England and Wales. Many of the larger remaining areas of downland are now nature reserves or military training grounds.
These grasslands are of big cultural and conservation importance and provide a range of ecosystem services such as carbon storage. Conserving and restoring these grasslands demands knowledge in how to create resilient grasslands in the age of climate change and the biodiversity crisis.
Our 66 grassland study sites vary in age, from centuries-old old-growth grassland to grassland that has only been reverted from arable land within the last two years. This variation gives us a good insight on how species composition and overall complexity of sites vary with age.
Last year we conducted a series of surveys looking at a wide range of taxonomic groups to look at diversity and complexity by conducting pollinator surveys, invertebrate suction sampling, botany surveys, and taking soil cores to look at the soil microbiology. To give you an indication of the species richness of these fields, the number of vascular plant species recorded on the transects ranged from 11 to 53 species. Currently we are still processing many of last year’s invertebrate samples and we found lots of interesting stuff! Some highlights discovered during the microscope peeking include the larvae of the rare Rugged Oil Beetle stuck to the legs of solitary bees in whose nests they develop, to samples from a single site with 12 species of weevil.
Clockwise from top left: flower-rich chalk grassland on a Wiltshire study site; Chiltern Gentian (Gentianella germanica); a study site dominated by Rough Hawkbit (Leontodon hispidus); Dark Green Fritilary (Speyeria aglaja) on Dwarf Thistle (Cirsium acaule); a field site in Hampshire with lots of Pyramidal Orchid (Anacamptis pyramidalis); Burnt-tip Orchid (Neotinea ustulata); English Longhorn cow and calf and Stonehenge as seen from one of our field sites placing this man-made habitat in a historic context.
This year we will be conducting more in-depth surveys over several of our study sites, looking at the soundscape and the diets of the predatory invertebrates amongst others. In March have set up several experimental plots in which we sowed additional plant species and added additional carbon and we will be monitoring this over the coming years to see if and how this affects diversity and complexity. The coming field season is promising to be an intense but exciting one. Hopefully we will be able to collect some good quality data and enjoy the lovely landscapes and species that cross our path.
Clockwise from top left: Adonis Blue (Polyommatus bellargus) on its larval food plant Horseshoe Vetch (Hippocrepis comosa); Vestal Cuckoo Bee (Bombus vestalis) on Wild Thyme (Thymus drucei); Cistus Forester (Adscita geryon); a larva of the Black Oil Beetle (Meloe proscarabaeus); a larva of the Rugged Oil Beetle (Meloe rugosus) hitching a ride on the leg of a Common Furrow Bee (Lasioglossum calceatum); Heath Snail (Helicella itala), and Glutinous Earthtongue (Glutinoglossum glutinosum).
All photos taken within our 60 grassland sites.
Photo credits: Maico Geert Weites
March 2022: How to create complex woodlands
By Prof Kirsty Park, Principal Investigator
As outlined in February’s blog, the aim of RestREco is to identify factors influencing the trajectory of ecosystem complexity during restoration – in this blog we’ll take a look at one of the two habitats we are focussing on: woodland.
Woodland is one of the most biologically diverse systems on Earth, but forest systems have been severely affected by habitat loss and their cover has been reduced by ca. 50% worldwide in the last three centuries. Remaining woodlands are often highly fragmented and degraded, consisting of many relatively small and isolated patches immersed in a sea of agriculture or urban conurbation.
Whilst we know quite a bit about the effects of woodland loss and fragmentation on wildlife, we know much less about the effects of “putting it back” i.e. woodland creation. In part, this is because of the very long-time scales over which woodlands grow and develop. In addition, it takes time for species to arrive and establish in new habitats (sometimes referred to as colonisation credits). All this makes it very hard to conduct experiments on appropriate spatial and temporal scales. However, we can use a ‘natural experiment’ approach, which has the potential to overcome some of the challenges of landscape-scale studies. Natural experiments overlay an experimental design on an ecosystem where change or active manipulation has occurred or is planned, beyond the control of the researcher. In RestREco, we have selected secondary woodlands established on land formerly used for industry (‘brown field’ sites) or agriculture. We then selected sites from a gradient of surrounding woodland since this is likely to influence the speed at which species can colonise new woodlands. Because these are all sites of known planting age (10-60 years old), we can look at how these factors interact over time to influence the structure and function of the species assemblages at these sites, and ultimately ecological complexity.
At a subset of these sites we will also be testing the effects of thinning and stacking brash around young trees, to examine how management interventions influence ecological function and complexity. Thinning (selective removal of trees) is a commonly used forestry technique to improve the quality and growth of the remaining trees. We also know that many woodlands have high herbivory pressure due to deer grazing on tree seedlings and saplings, which reduces regeneration, a crucial component of forest ecosystems. We hope to deter deer browsing by stacking brash around young trees, as a protection from this disturbance. We will be examining the effects of these interventions on measures of complexity and ecological function over the next two years.
Braving the Scottish summer weather and waist high stinging nettles, the woodland team have completed surveys on ecosystem complexity in 30 woodlands across Central Scotland. Surveys of trees, flowering plants and invertebrates, along with audio recordings of birds and bats will provide data on structural complexity and biodiversity. By characterising each of these components of woodland complexity, we can determine how age, former land-use and woodland in the landscape influences complexity. This summer we will continue these surveys in 30 more woodlands in the midlands of England, around the National Forest (project partners of RestREco), as well as carrying out more in-depth surveys into measures of ecosystem function in 18 of our Scottish woodlands.
Planting trees is just one way of creating woodland – recently, there has been considerable focus on natural colonisation, a process by which woodlands establish naturally from local seed dispersion. Both methods have their place depending on the local circumstances, but what is clear is that whichever method (or mix of methods) is used, it is more important than ever that the right mix of trees is planted (or natural colonisation facilitated) in the right places to ensure the multiple benefits we need from our landscapes in the future.
Other information and related projects:
Watts K, Whytock RC, Park KJ, Fuentes-Montemayor E, Macgregor NA, Duffield S & McGowan PJK (2020) Ecological time lags and the journey towards conservation success. Nature Ecology & Evolution
Woodland Creation and Ecological Networks, the WrEN project: https://www.wren-project.com/
All photos taken within our 30 woodland sites across Central Scotland
Photo credits: Dr Emily Waddell, Sam Rogerson and Ross Barnett
February 2022: Restoring Resilient Ecosystems
By Prof Jim Harris, Consortium Lead Principal Investigator
We are facing the Sixth Mass Extinction, coupled with rapid Climate Change and large-scale transformation of natural ecosystems for agriculture, mineral extraction and urbanisation. Although it comes as no surprise to many that we are utterly dependant on the biosphere for our continued existence, only in recent years have world governments become focussed on these challenges, and the need for urgent action.
Part of the solution is the need to ensure our ecosystems are “resilient”, so that they can continue to function in the face of the acute upswing in extreme events, such as droughts, flooding and wildfires. Such ‘Nature based solutions’ are beginning to gain widespread traction.
The United Nation has this year launched “The Decade on Ecosystem Restoration”, as a way of galvanising action to combat biodiversity loss, but also as a means of sequestering carbon. But what do we mean by “ecosystem restoration” and how can we assess if the restoration has been successful? – and why do we need this research programmes such as ours? We intend to measure biodiversity, architecture and multifunctionality in ecosystems in different stages of transition from a degraded state, identify determinants and measures of complexity, and seek signals of emergent properties – especially resilience to perturbation. We have chosen grasslands and woodlands, being two major habitat types targeted for restoration programmes. Further to this we shall explore how approaches to accelerating re-integration of systems may affect emergent properties. In summary, we propose to move restoration science forward, but considering complexity and resilience as fundamental aims for restoration projects, rather than attempting to re-create specific target ecosystems.
But surely restoration involves just “putting things back to how they were before”? If only it was that easy! Climate change has changed the “biophysical envelope” in many regions of the world – with variations in temperature and precipitation not seen for millennia, if not longer, and at a pace that is stretching, if not beyond the normal “plasticity” of ecosystems’ adaptive or evolutionary responses. Couple this with other anthropogenic pressures to systems, including intensifying species extinction, “going back” is no longer an option in many circumstances, and certainly doesn’t guarantee that it will be resilient in the future.
So, if we can’t simply aim to make systems the way they used to be, and recognising our current systems are themselves under pressure, how are we going to make decisions as to what kind of targets we should aim for? That is where our project is trying to find answers.
For a complex structure, such as the many habitats we benefit from, to be considered as a system, it needs to have a number of characteristics – diversity, complexity, function, and dynamic emergent properties – particularly, resilience. We aim to uncover the relationship between these characteristics on a range of sites under restoration management programmes. In this way the targets that we aim for may not need to be precisely those that existed in the past in terms of their species components, but rather have similar complexity, function and emergence – sometimes formulated as “same play, different actors”.
We shall be looking at everything from the soil microbial community, vegetation, invertebrates, birds and bats, trying to detect signals of complexity in structure and function, and what factors influence the trajectory of complexity during restoration for management. What is more, we will tie those signals to emergent properties of those systems.
We hope that this will give us another management tool alongside the tried and trusted methods based on ecosystems that we already recognise, as this approach applies as much to them as to any newly emergent assemblages of plants and animals which are beginning to appear, to give us confidence that we are making progress in securing an enduring future for our biodiversity and the ecosystems upon which we depend.